Biochemical pregnancy is a miscarriage that happens before the pregnancy can be seen with an ultrasound
A biochemical pregnancy is a pregnancy that stops growing and resolves before it becomes large enough to see it with ultrasound. “Biochemical” means that the only evidence that the pregnancy existed was the hCG (pregnancy hormone) showing up on a positive pregnancy test. Even though the pregnancy loss was early, it still counts towards the tally of pregnancies, and if it happens often, can indicate the need for additional testing.
What can be seen during a biochemical pregnancy?
A normal pregnancy must grow for a few weeks until it can be seen with ultrasound, usually around five and a half weeks of gestation, or about one and a half weeks after a missed period. At that time, the hCG (pregnancy hormone) level measures approximately 1,500 to 3,000 units. In a biochemical pregnancy, the pregnancy is typically lost prior to this time, before the hCG level rises high enough for the pregnancy to be visualized. Since the pregnancy stops growing before it gets to a certain size, the pregnancy can only be detected on bloodwork, not ultrasound.
Causes of early miscarriage
The vast majority of the time, a biochemical pregnancy is due to one or more chromosomal abnormalities within the very early embryo. This may occur when an abnormal egg is fertilized by a normal sperm, when an abnormal sperm fertilizes a normal egg, or when there is a mistake made during cell division following normal fertilization. These mistakes typically result in embryos that do not have the normal number of 46 chromosomes. Most chromosomal abnormalities cause the pregnancy to have a limited ability to grow and develop. When that limit is reached, development stops, and the pregnancy stops growing.
Embryos that do not have a normal number of chromosomes almost always stop growing and result in miscarriage. There are a few exceptions, such as Down syndrome, in which embryos can have an abnormal number of chromosomes, yet still result in a live birth. Typically, these babies have developmental defects that can range from mild to life-threatening.
Miscarriages are common, but having more than two means you need a professional evaluation
Biochemical pregnancy is common. However, if you have had two or more miscarriages, you should have an evaluation. There are many factors to consider for patients with recurrent pregnancy loss, and the workup often includes testing for uterine factors, antibodies, hormone imbalances and genetic problems, even in patients with biochemical pregnancies. Sometimes, a specific factor can be identified and treated to reduce the risk of miscarriage.
Our physicians at Texas Fertility Center in San Antonio would love to help. They will discuss with you all the possible causes of miscarriages and biochemical pregnancy, and will perform a comprehensive evaluation. They will then recommend treatment that can significantly increase your chances for a successful pregnancy. Contact us for an appointment.